Improvements in construction materials, construction methods, and more stringent local and state building codes have contributed to improved energy efficiency in new building construction and remodeled insulated wall structures for homes and buildings.
Conventional construction techniques employed to obtain relatively high insulation values involve a wall frame which supports insulation between an exterior wall or cladding, and an interior finishing surface of the wall. In some cases, polymer membranes are applied to the exterior cladding or sheathing as a water-impermeable barrier that nonetheless permits air exchange into and out from the wall. Additionally, low permeability polymer barriers are oftentimes applied to an inner portion of the wall structure, encasing the insulation between the inner low permeability polymer barrier and the exterior wall, casing, or cladding, with or without the presence of a gas-transmissive membrane at the exterior side of the wall.
Though the above-described arrangement has proven effective in creating a relatively high insulative value (R-value), the combination of an interior side vapor barrier has the tendency to cause moisture retention in the wall structure, which can undesirably lead to mold growth within the wall, degradation of the wall, insects, and/or other moisture related problems. The source of moisture within the wall structure is oftentimes condensation that occurs between a warm surface and a cold surface. The condensation typically forms as a result of warm and humid interior air moving to a cold exterior surface of the wall in winter months, or warm and humid exterior air moving to a relatively cold interior surface of the wall in summer months due to air conditioning. Not only does the retained moisture of condensation impact the structure of the wall itself, it can also reduce the insulative performance by creating a “liquid bridge” of relatively high thermal conductivity through the wall. Once moisture has accumulated in the wall, it is typically difficult with conventional construction arrangements to dry out the wall, or to maintain the moisture below a concentration that is potentially detrimental to the structural or performance characteristics of the wall. Drying of accumulated moisture, such as from condensation, is particularly challenging with high R-value wall constructions, which inhibit air movement through the wall.
In addition to conventional wall construction approaches of light timber framing supporting blown, rolled, or sheet insulation between upright framing studs, structural insulated panels have also been employed as pre-formed modular building panels. The structural insulation panels may be of a sandwich construction with an insulating foam core covered on each side by a sheeting material such as plywood or oriented strand board (OSB). Structural insulation panels may alternatively be a non-sandwich design which incorporates structural studs embedded or partially embedded in an insulation material. Such structural insulation panels may be formed by molding insulation material about, or bonding insulation material to one or more structural studs, which may typically be manufactured from steel or other inorganic material. Consequently, many modular wall panels available today utilize wood or metal framing construction studs in combination with an expanded polystyrene (EPS) foam.
Modular wall panels are useful in residential and commercial building construction since they make the assembly of wall frames more efficient. Essentially, a wall frame may be constructed simply by joining a series of preformed wall panels to one another. Conventional structural insulation wall panels, however, have also failed to adequately address the problem of moisture entrapment between external cladding and the building panels or other framework.
A particular application in the construction of insulated walls, either through conventional techniques or through modular structural insulated panels, is in the construction of insulated walls in a basement against or in proximity to the exterior foundation wall. While the construction of basement finishing walls is similar in many ways to the construction of above-ground exterior walls, construction of basement finishing walls is oftentimes undertaken by homeowners who are not necessarily skilled in best construction practices. Moreover, basement constructions are well known for moisture entrapment, such that techniques for limiting or preventing excessive moisture retention within the walls becomes particularly important in the basement setting. Conventional construction techniques also commonly employ wood structural components, which are susceptible to degradation in the presence of moisture.
Builders have recognized the need for constructing walls from materials which are resistant to moisture degradation, and to at least separate materials that are susceptible to moisture damage from a moisture source, such as the concrete wall of a basement foundation. However, no systems have been developed to date which permit both efficient and consistent construction of walls that are both resistant to damage by moisture, and prevent a “liquid bridge” between the moisture source and the interior of the wall surface so as to maintain a desirably high R-value insulation property.
It is therefore an object of the present invention to provide a wall construction system that is resistant to moisture degradation, and establishes an effective interior air barrier to limit condensation at an exterior sheathing as a result of moisture-laden interior warm air from reaching the cool exterior sheathing or wall.
It is another object of the present invention to provide a wall framing system that permits the efficient construction of a wall with a capillary break between the wall and an exterior sheathing or wall.
It is a still further object of the present invention to provide a wall framing system of materials which are resistant to degradation by moisture, and may include recycled content.
It is a further object of the present invention to provide a wall construction kit that facilitates the construction of a “best-practices” wall by non-professional builders.